The present invention relates to a conveying apparatus for conveying sheet material such as nonwoven fabric.
Conveying apparatuses that convey nonwoven fabric formed through the melt-blowing process have been known (for example, Japanese Laid-Open Patent Publication No. 2011-162915).
Such conveying apparatuses are structured to convey nonwoven fabric using rollers. These rollers are rotated by motors.
In recent years, nonwoven fabrics having low Young's moduli have been developed. When such nonwoven fabric is conveyed by a conveying apparatus, wrinkles and stretches are likely formed in the fabric. Therefore, the rollers must be rotated at low speeds, and rotations of the rollers must be synchronized so that the tension acting on the fabric between the rollers is maintained at a constant value. However, in a conveying apparatus that is configured such that rollers are rotated at low speeds, the lower the rotation speeds of the motors, the less stable the rotations of the motors, that is, the rotations of the rollers become. Thus, in reality, rotations of the rollers cannot be accurately synchronized, and wrinkles and stretches in nonwoven fabric are inevitable during conveyance of nonwoven fabric.
A structure has been proposed in which rotations of motors are transmitted to rollers via reduction gears to reduce the rotation speeds of rollers and synchronize the rotations of the rollers. This structure prevents rotations of the rollers from being unstable. However, since large-size reduction gears are required, the conveying apparatus has a complex structure.
These drawbacks are present not only in apparatuses for conveying nonwoven fabric, but also commonly found in apparatuses for carrying other types of sheet materials.